FFmpeg/libavfilter/avfiltergraph.h

/*
 * Filter graphs
 * copyright (c) 2007 Bobby Bingham
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVFILTER_AVFILTERGRAPH_H
#define AVFILTER_AVFILTERGRAPH_H

#include "avfilter.h"
#include "libavutil/log.h"

typedef struct AVFilterGraph {
#if FF_API_GRAPH_AVCLASS
    const AVClass *av_class;
#endif
    unsigned filter_count;
    AVFilterContext **filters;

    char *scale_sws_opts; ///< sws options to use for the auto-inserted scale filters
} AVFilterGraph;

/**
 * Allocate a filter graph.
 */
AVFilterGraph *avfilter_graph_alloc(void);

/**
 * Get a filter instance with name name from graph.
 *
 * @return the pointer to the found filter instance or NULL if it
 * cannot be found.
 */
AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name);

/**
 * Add an existing filter instance to a filter graph.
 *
 * @param graphctx  the filter graph
 * @param filter the filter to be added
 */
int avfilter_graph_add_filter(AVFilterGraph *graphctx, AVFilterContext *filter);

/**
 * Create and add a filter instance into an existing graph.
 * The filter instance is created from the filter filt and inited
 * with the parameters args and opaque.
 *
 * In case of success put in *filt_ctx the pointer to the created
 * filter instance, otherwise set *filt_ctx to NULL.
 *
 * @param name the instance name to give to the created filter instance
 * @param graph_ctx the filter graph
 * @return a negative AVERROR error code in case of failure, a non
 * negative value otherwise
 */
int avfilter_graph_create_filter(AVFilterContext **filt_ctx, AVFilter *filt,
                                 const char *name, const char *args, void *opaque,
                                 AVFilterGraph *graph_ctx);

/**
 * Check validity and configure all the links and formats in the graph.
 *
 * @param graphctx the filter graph
 * @param log_ctx context used for logging
 * @return 0 in case of success, a negative AVERROR code otherwise
 */
int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx);

/**
 * Free a graph, destroy its links, and set *graph to NULL.
 * If *graph is NULL, do nothing.
 */
void avfilter_graph_free(AVFilterGraph **graph);

/**
 * A linked-list of the inputs/outputs of the filter chain.
 *
 * This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(),
 * where it is used to communicate open (unlinked) inputs and outputs from and
 * to the caller.
 * This struct specifies, per each not connected pad contained in the graph, the
 * filter context and the pad index required for establishing a link.
 */
typedef struct AVFilterInOut {
    /** unique name for this input/output in the list */
    char *name;

    /** filter context associated to this input/output */
    AVFilterContext *filter_ctx;

    /** index of the filt_ctx pad to use for linking */
    int pad_idx;

    /** next input/input in the list, NULL if this is the last */
    struct AVFilterInOut *next;
} AVFilterInOut;

/**
 * Add a graph described by a string to a graph.
 *
 * @param graph   the filter graph where to link the parsed graph context
 * @param filters string to be parsed
 * @param inputs  linked list to the inputs of the graph
 * @param outputs linked list to the outputs of the graph
 * @return zero on success, a negative AVERROR code on error
 */
int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
                         AVFilterInOut *inputs, AVFilterInOut *outputs,
                         void *log_ctx);

/**
 * Add a graph described by a string to a graph.
 *
 * @param[in]  graph   the filter graph where to link the parsed graph context
 * @param[in]  filters string to be parsed
 * @param[out] inputs  a linked list of all free (unlinked) inputs of the
 *                     parsed graph will be returned here. It is to be freed
 *                     by the caller using avfilter_inout_free().
 * @param[out] outputs a linked list of all free (unlinked) outputs of the
 *                     parsed graph will be returned here. It is to be freed by the
 *                     caller using avfilter_inout_free().
 * @return zero on success, a negative AVERROR code on error
 *
 * @note the difference between avfilter_graph_parse2() and
 * avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides
 * the lists of inputs and outputs, which therefore must be known before calling
 * the function. On the other hand, avfilter_graph_parse2() \em returns the
 * inputs and outputs that are left unlinked after parsing the graph and the
 * caller then deals with them. Another difference is that in
 * avfilter_graph_parse(), the inputs parameter describes inputs of the
 * <em>already existing</em> part of the graph; i.e. from the point of view of
 * the newly created part, they are outputs. Similarly the outputs parameter
 * describes outputs of the already existing filters, which are provided as
 * inputs to the parsed filters.
 * avfilter_graph_parse2() takes the opposite approach -- it makes no reference
 * whatsoever to already existing parts of the graph and the inputs parameter
 * will on return contain inputs of the newly parsed part of the graph.
 * Analogously the outputs parameter will contain outputs of the newly created
 * filters.
 */
int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
                          AVFilterInOut **inputs,
                          AVFilterInOut **outputs);

#endif /* AVFILTER_AVFILTERGRAPH_H */